I created a multi-body system and tried to compute its kinematics. I found that the body rotation matrix from Mujoco and my computation is the same when I use the integrator "Euler" in XML but "RK4". What is different between the two integrators? Kinematic computation is not related to the integration process so it might be the same. However, the rotation with RK4 has some messy bits even in the axis of rotation. For example, It has expected to be [0, 0, 1] for the z-axis but it becomes [0.00xxx, 0.00xx, 1].